KR20070007957A - A deformation-sensing bearing having four stress gauges - Google Patents

Abstract

The invention relates to a bearing comprising at least one system for determining the amplitude A of pseudo- sinusoidal deformations induced during rotation of a fixed ring (1) area (7), wherein said system comprises four stress gauges (8), a device for measuring four signals Vi based on time variations of a signal emitted by each gauge (8) and for forming two signals SIN and COS for the same angle and amplitude and a device for computing the time-dependent amplitude A of the area (7) deformations for calculating a SIN2 + COS2 expression in such a way that the amplitude A is derived therefrom. ® KIPO & WIPO 2007

Description

A deformation-sensing bearing having four stress gauges}

The present invention relates to a fixed or "stationary" ring, a rotating ring and rolling bodies disposed in a raceway formed between the rings such that the rings can rotate relative to one another. A bearing comprises one or more rows.

This generally applies to automotive wheel bearings, where the stop ring is installed on a wheel associated with the chassis and the rotating ring of the vehicle.

It is known that when trying to measure the force exerted on the interface between a wheel and the surface on which the wheel is rotated, it is possible to measure the force on the tire or chassis.

Unfortunately, measurement of a tire introduces a number of problems associated with the transmission of signals between a tire's rotational reference frame and a stationary reference frame, in order to perform the operation the rotational reference frame continues to the stationary reference frame. Should be associated with Measurements on the chassis are difficult due to the distribution of forces between the various members connecting the wheels to the chassis.

Thus, as shown in documents FR-2 839 553 and FR-2-812 356, the first connection between the wheels and the chassis, as a support, to measure the force exerted on the interface between the wheels and the surface while the vehicle is moving A stop ring that is a member is used.

In particular, such a force can be measured by measuring the deformation in the stationary ring caused by a passing cloud sieve. The magnitude of such deformation is indicative of the force being measured.

One of the problems caused by such a force measuring method is that the strain signal is dependent on the rotational speed. In particular, the measurement quality at low velocities is insufficient and the force can only be measured after measuring the deformation caused by the passing of at least two rolling bodies in succession.

Thus, such a problem is, for example, as the measurement of force is essential for systems that control the power of a vehicle, such as the Antilock Braking System (ABS) or the Electronic Stability Program (ESP). This is more critical if it should be done in real time or with the shortest delay possible.

The main object of the present invention is to solve this problem by presenting a bearing having a system for measuring the magnitude of the deformation in the stationary ring, which system at any time and independently of the rotational speed obtains a measurement of the deformation to force It is arranged to perform spatial interpolation on the deformation signal so that it can be measured.

Finally, the present invention provides a bearing comprising a stop ring, a rotating ring, and a row of one or more rows of rolling bodies disposed in a raceway formed between the rings such that the rings can rotate relative to each other, wherein The rolling bodies are evenly distributed on the raceway at angular spacing λ, and the bearing measures the amplitude A of the pseudo-sinusoidal deformation of the stationary ring region caused during rotation. And at least one measuring system wherein the measuring system in the bearing comprises:

Four strain gauges uniformly distributed on the area and transmitting signals as a function of the deformation the gauge receives;

- rotation for a time variation of and measure the four signals V _i a function of the four signals by combining V _i, the two signals of the same size a function of the same angle, and A of a signal to be generated by each of the gauge A measuring device for generating SIN and COS; And

Calculate the size A of the deformation region as a function of time and use SIN ² to derive the size A. A computing device arranged to calculate + COS ² .

Other objects and advantages of the invention will appear as set forth below with reference to the accompanying drawings.

1-3 are perspective views of gauges of four systems, each measuring three magnitudes of pseudo-sinusoidal deformations, disposed on each region of the stop ring, as three embodiments of the bearing.

4 is a circuit diagram according to a first embodiment of a measurement system according to the present invention.

5 and 6 are circuit diagrams relating to a second embodiment of the measurement system according to the invention.

FIG. 7 is a schematic diagram showing the specific arrangement of the gauges associated with the angular spacing between rolling bodies in the stationary ring of the bearing of FIG. 1.

FIG. 8 is a view similar to FIG. 7 showing a distance between the gauge and the raceway.

The present invention provides a fixed or "stop" ring 1, a rotating ring and rolling bodies 2 arranged in a raceway 3 formed between the rings so that the rings can rotate relative to each other. To a bearing comprising at least one of the rows.

The stop ring 1 is designed to engage a stationary or "stop" structure, and the rotary ring is designed to engage a rotating member. In a particular application, the bearing is an automobile wheel bearing, the stop structure is an automobile chassis, and the rotating member is a wheel.

1 to 3, such wheel bearings are arranged with respect to a common axis in each raceway 3 provided between an outer stop ring 1 and an inner rotary ring. It appears to include two rows for ball 2). The stop ring 1 also has fastening means for fastening with the chassis, which fastening means comprises four radial protrusions 5 with axial holes 6 which allow fastening by bolting. It is formed by the flange (4) having a.

As shown in FIGS. 7 and 8, the balls 2 are evenly distributed in the raceway 3 at angular spacing λ, also referred to as a “spatial period”. In a known form, the spacing between the balls 2 is maintained by placing them in a cage.

The present invention makes it possible to measure the magnitude of the deformation of at least one of the regions 7 of the stop ring 1, thereby deriving a force exerted on the interface between the wheel and the surface on which the wheel is rotated. It is intended to be.

The ball 2 rolling along the raceway 3 induces compression and relaxation to the stop ring 1. Thus, during rotation, a periodic strain occurs in the stop ring 1, which is approximately sinusoidal. In the following description, the term "pseudo-sinusoidal deformation" is used as referring to the deformation of the stop ring during rotation.

The quasi-sinusoidal deformation is characterized by the magnitude depending on the load on the bearing and thus the force on the interface, and the frequency proportional to both the speed of rotation of the rotating ring and the number of balls 2.

Although described with reference to a wheel bearing having two rows of balls 2 in which the magnitude of the deformation is measured independently, those skilled in the art have described the above description in the pseudo-sinusoidal curve of one or more regions 7 of the stop ring 1. It can be applied directly to other types of bearings and / or other applications where the size of the mold deformation is to be measured.

According to the invention, the bearing has at least one system for measuring the magnitude (A) of the pseudo-sinusoidal deformation of the region of the stop ring (1) 7 caused during rotation, the system having four strains Gauge 8 is provided.

Each gauge 8 is suitable for transmitting a signal as a function of the deformation it receives. As shown in FIGS. 1-3, the gauges 8 are evenly distributed on the area 7 along a line extending in the general direction of rotation.

The measuring system also further comprises a measuring device 9 for measuring the four signals V _i a function of the time variations in the signal generated by each of the gauge (8) during the rotation, the measuring device, the four signal By combining V _i , it is suitable for generating two signals SIN and COS that are the same magnitude as a function of the same angle and A.

From the two signals SIN and COS, for example, through the computing device 10 consisting of a processor SIN ² It is possible to derive size A by calculating + COS ² .

Thus, since the magnitude is calculated independently of the rotational speed, it is possible, in particular, to overcome the problems relating to the quality inherent in the temporary measurement of delay or deformation.

4 to 6, the gauges 8 are based on resistive elements, in particular piezoresistive or magnetostrictive elements, so that each of them functions as a function of the deformation that the gauge 8 receives. The first and second embodiments of the measuring system according to the present invention having an electrical resistance R _i changed to are described below. In particular, each gauge 8 may comprise a single resistor, or a plurality of resistor blocks combined to obtain an average resistance representing the resistance at the location of the block as meaning a single resistor.

In the two embodiments described, the measuring device 9 comprises a current loop circuit between four gauges 8. The circuit further includes four differential amplifiers 11 with adjustable gain G _i . In addition, the measuring device 9 may further comprise a signal filter stage (not shown).

Thus, the measuring device 9 transmits the following signals at the output of the amplifier 11:

Where R _0i is the resistance in the remaining resistors R _i , ΔR _i is the change in resistance in the gauge 8, ω = 2π / T (T is the time), φ is the space in between the gauges 8 Phase shift, i, is the current in the loop.

The nature of the sinusoidal (time related) of the sample function is used to simplify the following operations, but is not so limited. This premise assumes the bearing rotates at a constant speed (ω constant).

In the embodiment shown in FIG. 4, the measuring device 9 further comprises a stage of the differential amplifier 11 arranged to obtain the following differences:

Adjust the output gain G _i to G ₁ = G ₂ = G ₃ = G ₄ = G, the resistors on the remaining resistors to R ₀₁ = R ₀₂ = R ₀₃ = R ₀₄ , ΔR ₁ By assuming that ΔR ₂ = ΔR ₃ = ΔR ₄ = ΔR, Equations 1 and 2 above are as follows:

In particular, the identity of the ΔR _i value is obtained when the gauge 8 is at the same distance from the raceway.

In particular, when φ = π / 2, that is, when the gauge 8 is spaced apart at a distance equal to λ / 4, Equations 3 and 4 above can be expressed as:

Thus, in this particular case, the measuring device 9 shown in FIG. ₄ makes it possible to obtain the signals COS = V ₁ -V ₂ and SIN = V ₃ -V ₄ directly.

을 얻는 것이 가능하고, 이에 따라 연산 장치(10)의 출력부에서, ΔR 에 관한 함수인 크기 A를 시간에 관한 함수로서 얻는 것이 가능하도록 한다.Thus, SIN ² + By calculating COS ²

It is possible to obtain, so that at the output of the arithmetic unit 10, it is possible to obtain the magnitude A which is a function of ΔR as a function of time.

5 and 6, the measuring device 9 which can obtain the SIN and COS signals without considering the phase change? Value between the gauges 8 will be described later.

For this purpose, the measuring device 9 further comprises two stages of differential amplifiers 11 whose first stage is proportional to the amplifier stage of the first embodiment of FIG. 4, whereby the measuring device is described above. Equations 3 and 4 are used to convey not only signals V ₁ -V ₂ and V ₃ -V _4, but also signals V ₁ -V ₃ and V ₄ -V _{2 in a} similar manner (FIG. 6).

The second stage has two differential amplifiers 11 for conveying the following signals, respectively shown in FIGS. 5 and 6 for clarity:

U = [(V ₁ -V ₂ )-(V ₃ -V ₄ )]; And

V = [(V ₁ -V ₃ )-(V ₄ -V ₂ )]

That is, based on Equations 3 and 4,

Thus, as described above, U = SIN and V = COS and SIN ² in the computing device 10. By calculating + COS ² , one can obtain size A which is a function of ΔR.

If φ is different from π / 2, the magnitudes of the signals U and V are also different. In order to make these sizes the same, it is possible to make a preliminary measure for one or more second stage differential amplifiers 11 to have adjustable gain. In particular, the gain of the amplifier 11 forming the signal U can be adjusted as follows:

In the modified embodiment shown in FIGS. 5 and 6, the second stage of the measuring device 9 is adapted to carry an amplifier 11 and a signal V = 2 (V ₂ -V ₃ ) as shown in FIG. 5. A second amplifier 11 arranged. Thus, the signals transmitted by the measuring device 9 are as follows:

U = [(V ₁ -V ₂ )-(V ₃ -V ₄ )]; And

V = 2 (V ₂ -V ₃ )

This variant is particularly suitable when the magnitudes of the signals V _i are not considered equal, ie when the gauge does not detect a sine wave of the same magnitude A. Assuming a linear load distribution between the four gauges (8), the signals V _i may be represented as follows:

Where a is the linear deformation in the measured size A.

To simplify the calculation, assuming φ = π / 2, the interpretation in this variant is applicable to any φ value, and we get the following equation:

Thus, U = SIN and V = COS, SIN ² + The square root of COS ² is

Therefore, if the first order is limitedly expanded (a < A), a size A is obtained, which is a size derived from the center of the region where the gauge 8 is distributed.

7 and 8 show gauges 8 spaced apart by a distance equal to [lambda] / 4, which are arranged in a substantially planar deformation region. As shown in FIG. 8, the gauges 8 are d _1. = d ₄ And d ₂ each distance d ₁ , d ₂ , d ₃ , d _{4 with} = d ₁₃ It is centered in the area so that it is spaced apart from the raceway.

Depending on the particular configuration of this gauge 8, the following relation holds:

Here, R ₁ is further away from the raceway than R ₂ , and thus ΔR ₂ = kΔR ₁ and k> 1 since the signal from the deformation of R ₁ will be smaller than the signal from R ₂ .

And, due to the symmetry of the strain in the gauge 8 in the deformation region 7, it can be expressed as follows:

ΔR ₃ = kΔR ₄ = ΔR ₂ = kΔR ₁

Also, the gain is adjusted such that G ₁ ΔR ₁ = G ₂ ΔR ₂ = G ₃ ΔR ₃ = G ₄ ΔR ₄ .

Thus, from the above relation, it is obtained as follows:

G ₁ = kG ₂ = G ₄ = kG ₃

In this particular configuration, the resistance in the remaining resistors is as follows:

R ₀₂ = kR ₀₁ ;

R ₀₃ = kR ₀₄ ; And

R ₀₂ = kR ₀₃ .

Thus, in the configuration of the gauge 8 of Figs. 7 and 8, the condition regarding the gain value and the remaining resistance value of the resistor is determined to obtain the size A.

In the general case where the gauge 8 is located at the cylindrical periphery of the outer ring 1, the distances from the gauge to the raceway are all equal and k = 1. Thus, in all cases, the gain is the same and the resistance in the remaining resistors must also be the same.

With reference to FIGS. 1 and 2, the arrangement of the bearings in which the gauge is arranged on the substrate 12 fixed to the deformation region 7 of the stop ring 1 will be described later. The substrate 12 is firmly fixed to the stop ring 1, for example by adhesive bonding or welded bonding, so that it is also used to transfer the strain between the stop ring 1 and the gauge 8.

Although the gauge 8 described above is based on a resistive element, it is selected from other gauges 8, for example a surface acoustic wave sensor and a magnetic field sensor, as long as it carries a signal that is a function of deformation. These can also be used within the scope of the present invention. In particular, the magnetic field sensor can be based on high-sensitivity devices such as magneto-resistance, large magneto-resistance, hall effect, tunnel-effect magneto-resistance, and magnetostrictive layers.

In the embodiment described, the gauge 8 is screen printed in a thick layer, for example on a substrate 12 made of ceramic. In particular, the hybrid type technology allows the integration of the measuring device 9 and the computing device 10 on the substrate 12 (see the embodiment of FIG. 2). In addition, screen-printing not only allows good resistance control and deformation in the resistor to be obtained, but also ensures the correct placement of the resistor on the substrate 12.

Deformation region 7 is substantially planar and is made to extend over two rows of balls 12. In this embodiment, the gauges 8 are not equidistant from the raceway, so the magnitude of the strain measured is a function of the gauge 8 (see FIGS. 7 and 8).

In the embodiment shown in FIG. 3, a provision may be made for the gauge 8 to be fixed directly to the curved surface of the stop ring 1, for example the gauge 8 may be in the form of a foil strain gauge. With this configuration, it is possible to make all distances between the gauge 8 and the raceway 3 equal.

In the embodiment shown in FIGS. 1 and 2, the gauges of the two measuring systems are integrated on the same substrate 12, so that around each raceway 3, in order to measure the magnitude of the deformation of the area 7. One or more measurement systems are provided.

In particular, the gauge 8 is arranged at the outer periphery of the stop ring 1 and substantially faces each raceway 3 to increase the strength of the signal being measured. Thus, the substrate 12 with the gauge 8 makes it possible to measure the magnitude of the strain each generated by the balls 2 in one row, essentially in the same axial plane.

The bearings are arranged at least three (8 in the embodiment shown in FIG. 1: four visible and symmetrically arranged at the other side of the bearing) for measuring the magnitude of the deformation in each region 7 of the stop ring. Four) systems, which are used to calculate the force exerted during rotation in an element fixed or integrated in the stationary ring 1 and / or the rotating ring as a function of measured magnitude. It is designed to be connected to or be connected to a suitable computer. In particular, such computers are described in Applicant's document FR-2 839 553.

Claims (20)

A bearing comprising a stop ring (1), a rotating ring and one or more rows of rolling bodies (2) arranged in a raceway (3) formed between the rings so that the rings can rotate relative to each other, The rolling bodies 2 are evenly distributed in the raceway 3 at angular spacing λ, and the bearing has a size A of the pseudo-sinusoidal deformation of the stationary ring 1 region 7 caused during rotation. One or more measuring systems for measuring, wherein the measuring system in the bearing: Four strain gauges 8 uniformly distributed on the area 7 and carrying signals as a function of the deformation the gauge receives; - and measuring the four signals V _i a function of the time variations in the signal generated by each of the gauge (8) during the rotation, by combining the four signals V _i, equal to a function of the same angle and A size of A measuring device 9 for generating two signals SIN and COS; And Calculate the size A of the deformation region 7 as a function of time and use SIN ² to derive the size A + A bearing, characterized in that it has a computing device (10) arranged to calculate COS ² . The method of claim 1, The gauge (8) is characterized in that it is based on a resistive element, so that each of them has an electrical resistance R _i which varies as a function of the deformation the gauge receives. The method of claim 2, The measuring device 9 comprises a current loop circuit between four gauges 8, the circuit comprising four differential amplifiers 11 with adjustable gain G _i . . The method of claim 3, wherein The gauge (8) being spaced apart at a distance equal to [lambda] / 4. The method of claim 4, wherein The measuring device (9) further comprises a differential amplifier (11) of one stage arranged to obtain V ₁ -V ₂ = COS and V ₃ -V ₄ = SIN. The method according to claim 3 or 4, The measuring device 9 further comprises a differential amplifier 11 of two stages, wherein the first stage is V ₁ -V ₂ , V ₃ -V ₄ , V ₁ -V ₃ , and V ₄ -V Arranged to obtain ₂ , the second stage being equal to [(V ₁ -V ₂ )-(V ₃ -V ₄ )] = SIN and [(V ₁ -V ₃ )-(V ₄ -V ₂ )] = Bearing arranged to obtain a COS. The method according to claim 3 or 4, The measuring device 9 further comprises a differential amplifier 11 of two stages, the first stage being arranged to obtain V ₁ -V ₂ and V ₃ -V ₄ , the second stage being [( V ₁ -V ₂ )-(V ₃ -V ₄ )] = SIN and 2 (V ₂ -V ₃ ) = bearings arranged to obtain a COS. The method according to claim 6 or 7, Bearing characterized in that the at least one second stage differential amplifier (11) has an adjustable gain. The method according to any one of claims 2 to 8, Bearing characterized in that the gauge (8) has a resistance of the remaining R ₀₁ equal to each other. The method according to any one of claims 2 to 8, The deformation region 7 is made to be substantially planar, the gauge is centered in the region so that it is equidistant from the raceway in pairs, and the gauge 8 is R ₀₂ = kR ₀₁ at the remaining R ₀₁ . Bearing having a resistance of R ₀₃ = kR ₀₄ , and R ₀₃ = R ₀₂ . The method of claim 1, The gauge (8) is a sensor characterized in that it comprises or comprises sensors selected from surface acoustic wave sensors and magnetic field sensors. The method according to any one of claims 1 to 11, The gauge (8) is characterized in that it is arranged on a substrate (12) fixed to the deformation region (7) of the stop ring (1). The method of claim 12, The gauge (8) is characterized in that the screen printed in a thick layer on the substrate (12). The method according to claim 12 or 13, Bearing, characterized in that the measuring device (9) and the computing device (10) are integrated on the substrate (12). The method according to any one of claims 1 to 14, Bearings, characterized in that at least three measuring systems are provided for measuring the magnitude of deformation in each region (7) of the stop ring (1). The method of claim 15, The system can be connected to or can be connected to a computer suitable for calculating the force exerted during rotation in an element fixed or integrated with the stationary ring 1 and / or the rotating ring as a function of measured magnitude. Bearing characterized in that it is designed. The method according to any one of claims 1 to 16, The gauge (8) is characterized in that it is arranged on the area (7) along a line extending in the general direction of rotation. The method according to any one of claims 1 to 17, Bearing, characterized in that the gauge (8) is arranged around the raceway (3). The method of claim 18, The gauge (8) is arranged in the outer periphery of the stop ring (1), characterized in that the bearing substantially faces the raceway (3). The method of claim 18 or 19, At the periphery of the raceway 3, it has two rows of rolling bodies 2, each arranged on one raceway 3, the bearing having at least one measuring system for measuring the deformation size of the region 7. Bearing provided.

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